Movement of substances in and out of the cell Flashcards
What is diffusion?
The movement of particles from an area of high concentration to an area of lower concentration down a concentration gradient.
Give two examples of diffusion in living organisms.
- Gas exchange in humans
- Gas exchange in plants
How does surface area to volume ratio affect diffusion?
A larger surface area to volume ratio increases the rate of diffusion.
How does diffusion distance affect the rate of diffusion?
A shorter diffusion distance increases the rate of diffusion.
Example: Alveoli have thin walls to provide a shorter diffusion distance for faster gas exchange.
How does the concentration gradient affect diffusion?
A steeper concentration gradient increases the rate of diffusion.
How does temperature affect diffusion?
Higher temperature increases diffusion rate because particles gain more kinetic energy and move faster.
How does particle size affect diffusion?
Smaller particles diffuse faster.
What is osmosis?
The movement of water molecules from a high water potential (dilute solution) to a lower water potential (concentrated solution) through a semi-permeable membrane.
What happens to an animal cell in a dilute solution?
Water moves into the cell by osmosis, causing it to swell and burst (as it has no cell wall).
What happens to an animal cell in a concentrated solution?
Water moves out of the cell by osmosis, causing it to shrink.
What happens to a plant cell in a dilute solution?
Water moves into the cell by osmosis, making it turgid (it does not burst due to the presence of a cell wall).
What happens to a plant cell in a concentrated solution?
Water moves out by osmosis, causing the cell to become flaccid or plasmolysed.
What is active transport?
The movement of particles from a low concentration to a high concentration against a concentration gradient using energy.
